Conventionally, a data carrier system constituted by a data carrier and a reader/writer device to perform contactless data transmission and reception between the data carrier and the reader/writer device is practically applied in various fields. In such a data carrier system, an antenna installed in the data carrier receives an alternating magnetic field of a carrier frequency supplied from the reader/writer device via an antenna circuit to obtain operating power.
Further, it is constituted so that the reader/writer device modulates the magnetic field that it supplies and transmits an inquiry signal including a command and data, and the data carrier demodulates the inquiry signal to receive the command and the data transmitted from the reader/writer device.
By contrast, in the case when the data carrier transmits data to the reader/writer device, an on/off operation of a well-known load switch is performed for a load connected to an antenna circuit installed in the data carrier in accordance with the contents of a response signal to be sent, and thereby, the response is sent. In such a way, it is constituted so that double sideband subcarriers are used as a frequency for responding from the data carrier, with respect to the carrier frequency of the alternating magnetic field supplied from the antenna circuit of the reader/writer device.
The data carrier is constituted to be provided with a storage section to store information and an antenna to transmit/receive information in a contactless manner in order to transmit and receive information in a contactless manner to/from the reader/writer device in use of electromagnetic fields or radio waves, and such a data carrier is utilized in various fields, being referred to as various names such as an RFID, an IC tag, an ID tag, an RF tag, a wireless tag, an electronic tag, a transponder, and the like.
As application examples of the above-described data carrier system, a data carrier is disposed to, for example, vending machines, game machines, electricity meters, gas meters, water meters, home electronics, office automation equipment, productive facilities, and the like, and information such as operation histories, sales records and used amount of these electronic devices is recorded in the storage section of the data carrier.
Since the data carrier is used in various fields, a usage mode thereof varies accordingly, however, there has been suggested technique to confirm whether a device component to which a data carrier is attached is authorized in advance by performing predetermined communication between the data carrier and a reader/writer device (for example, see Patent Document 1).
According to “system for managing consumables in electronic equipment” disclosed in Patent Document 1, data communication is performed between a data carrier attached to a device component and a reader/writer device provided in a device body in which the device component is installed, and thereby, it is possible to read various information stored in the data carrier or to store various information in the data carrier from the reader/writer device.
There is provided a security function in order to prevent information written in the data carrier from being read falsely, or false information from being written in the data carrier. Thereby, only a reader/writer device to transmit a password assigned to the data carrier is allowed to communicate with the data carrier. Accordingly, false access by a third person who does not know the password of the data carrier can be prevented.
Patent Document 1: Japanese Patent Application Laid-Open No. 2001-134151